The present invention relates to the field of liquid detergent compositions, in particular to coloured, highly concentrated liquid detergent compositions.
In general dyes used to colour liquid detergent compositions are water soluble and can be used without difficulty in standard aqueous liquid detergent compositions. Instead of a water-soluble dye, a pigment may be used to colour the liquid detergent composition. Many pigments are known in the art and it is not difficult to obtain the right colour and the right intensity. Pigments have been suggested in EP-A-344909 as an ingredient for non-aqueous liquid compositions. U.S. Pat. No. 5,759,981 describes a non-aqueous bleaching liquid wherein the bleaching system contains a bleach catalyst (manganese phthalocyanine) and a perborate bleach. However, the incorporation of pigments in such a highly concentrated liquid detergent is still problematic. Liquid detergent compositions comprising pigments are difficult to stabilise because the pigments tend to flocculate over time making the product commercially unacceptable. Liquid detergent compositions may be sold in clear containers such as water-soluble films, but many pigments are not colour stable in such containers. Furthermore, pigments in such concentrated liquid detergents may cause spotting on laundry items. WO-A-99/00477 discloses nonaqueous liquid detergent compositions containing 400-1,500 micron speckles which contains conventional dyes or pigments.
Surprisingly, we have found that one or more of these problems can be solved by the present invention. The present invention provides a concentrated liquid detergent composition comprising
1-90% of a nonionic surfactant,
1-60% of an organic solvent, and
0.0001-2% of a pigment
wherein more than 90% of the pigment particles have a particle size of less than 50 micron, preferably less than 30 micron, more preferably less than 10 micron, most preferably less than 1 micron. The pigment is dispersed in the composition in the form of particles of these specified sizes.
Another embodiment of the present invention relates to a process for preparing a concentrated liquid detergent composition comprising nonionic surfactant, an organic solvent and pigment, said process comprising the steps of
mixing the nonionic surfactant with the organic solvent,
adding to this mixture the pigment in the form of a pigment premix, and
adding remaining ingredients.
Accordingly, the advantages of the inventive composition are that the composition, does not cause visible pigment spotting on the laundered clothing, the coloured liquid detergent compositions are colour stable in transparent containers and/or that the composition is stable, i.e. the pigments remain homogeneously dispersed in the liquid detergent composition after at least 6 wks storage at 37xc2x0 C.
Neither EP-A-344909 nor U.S. Pat. No. 5,759,981 describes the above mentioned problems or suggests that the selection of this particle size distribution of the pigments would have these advantages.